President Trump’s popularity would rocket “through the roof” if he would just keep one promise that became a national mantra during the 2016 campaign, says best-selling author and conservative firebrand Ann Coulter.

And that promise is to build a wall on America’s southern border with Mexico.

Coulter made the comment on SiriusXM’s “Breitbart News Daily” in a discussion with Alex Marlow, Breitbart’s editor in chief.

Marlow called the matter “a total ticking time bomb,” saying, “There’s no wall, there’s no plan for a wall, and I’m very disturbed by it because I think this puts the entire presidency in the balance if the wall does not get built. And there is no one taking it seriously, apparently not even in the White House at this point.”

Coulter responded: “I know. The original sin was Trump hiring all these establishment, swampy Never-Trumper types. No, no one is there to tell him ‘Hey remember that promise you campaigned on and every single campaign rally with 10, 20, 30,000 people two or three times a day?’ Remember what chant they were saying? Was it ‘I will hire half of Goldman Sachs? No, it was not Mr. President.’ No, he has no one to tell him that.”

Coulter called Trump’s wall promise a “secret weapon,” if he would just go full force in deploying it.

“I just wish Trump would realize, that of all secret weapons of our secret weapons of Donald Trump, if he’d build the wall, the media will go crazy, it will distract over everything, and his poll numbers will go through the roof,” she said.

Ann Coulter

“There’s a reason … we wanted the wall and that is so that all of us don’t have to be on constant, constant alert for the next wave of illegal, poverty-stricken, very needy, uneducated immigrants pouring across our border.”

Coulter said she and independent media need to “kick into gear and we have to tell the truth about what’s going on and demand information. No, we wanted to get back to our lives and not keep fighting each one of these onslaughts.”

As WND reported, President Trump said Sunday he supported a government shutdown over the border crisis.

“I would be willing to ‘shut down’ government if the Democrats do not give us the votes for Border Security, which includes the Wall,” Trump tweeted. “Must get rid of Lottery, Catch & Release, etc., and finally go to system of Immigration based on MERIT! We need great people coming into our Country!”

This declaration sets up a clash between the White House and Republican congressional leadership following meetings between the president, House Speaker Paul Ryan and Senate Majority Leader Mitch McConnell in which the Trump was lobbied to leave immigration out of the spending fight.

It didnt take long for Trump to provide his answer.

Democrats have been dead-set against funding the wall without legislation that would keep DACA – the Deferred Action for Childhood Arrivals. That would mean Trump would need consensus from Republicans, which has also proved elusive.

Trump’s reference to “Catch & Release” is the policy that results in the release of illegal aliens while asylum claims are adjudicated. Ultimately, it is the policy that led to the separation of some 2,500 children from their families – an issue Democrats exploited politically.

The president also insists that all immigration should be based on applicants demonstrating they represent valuable assets to the country, rather than be based on the diversity visa-lottery program and family ties.

Meanwhile, Ryan and McConnell, facing the November midterm election that could result in changes of power in the House and Senate, are leery about a government shutdown that could prove unpopular in the weeks ahead.

In May, Trump suggested “closing up the country for a while” if he did not get his wall.

“They don’t want the wall,” Trump said. “But we’re going to get the wall, even if we have to think about closing up the country for a while.”

Sunday’s shutdown threat from Trump also echoed a remark he made in February when he said “I’d love to see a shutdown” if the government did not agree to address immigration.

Congress ultimately passed a spending bill in March that funded the government through September. Trump threatened at the time to veto the spending agreement, but eventually signed the bill while expressing his displeasure with Congress.

“I said to Congress, I will never sign another bill like this again,” Trump said in March.

In another tweet on the subject Sunday, Trump wrote: “Please understand, there are consequences when people cross our Border illegally, whether they have children or not — and many are just using children for their own sinister purposes. Congress must act on fixing the DUMBEST & WORST immigration laws anywhere in the world! Vote ‘R.’”

Americans are divided along party lines on immigration, with 81 percent of Republicans approving Trump’s handling of the issue, according to a Reuters/Ipsos poll released this month.